1. Field of the Invention
The present invention relates to a method and apparatus for lifting successive rings of corrugated steel panels to construct cylindrical grain bins.
2. Background of the Invention
Modem grain bins typically have cylindrical steel walls and conical steel roofs assembled from prefabricated components. The cylindrical steel wall of a modem grain bin is fashioned from curved steel panels having horizontal corrugations. Bolt holes are located about the edges of the curved steel panels so that panels can be fastened to the lower edge of an assembled roof and to each other in successive rings to complete a bin. Accordingly, the present method for assembling a grain bin generally includes the following steps: (a) laying a concrete foundation, (b) constructing a circular roof, (c) lifting the roof, (c) attaching a first ring of panels, (d) raising the roof and the first ring of panels, (e) attaching a second ring of panels to the first ring, and (f) attaching successive rings of panels to complete the bin.
Although the process for building a grain bin may seem simple, building a grain bin using present methods is really quite difficult and labor intensive. The most difficult part of bin construction is raising the successive circular rings of panels so that all parts of the structure stay level and lift at the same rate. If this is not done properly, parts of the structure will be overloaded and will fail. One bin raising method is to attach a pattern of jacks around the wall of the grain bin and carefully operate those jacks to incrementally raise each portion of the grain bin wall. In order to not over-stress the wall panels, all the jacks must be operated in small increments or simultaneously. Such incremental operations or simultaneous manual operations require significant labor. Another method for lifting a grain bin includes the use of an overhead crane. This method is difficult because a single point suspension of a large grain bin is inherently unstable. A multi-point suspension of a large grain bin is subject to the same difficulties as a multi-point jacking operation.
The difficulty encountered by those constructing grain bins is further aggravated by the continuing shortage of labor in rural areas. In the United States, at the beginning of the twentieth century, large numbers of workers could be found in rural areas. Today, at the beginning of the twenty first century, rural areas in the United States are depleted of labor and increasing levels of mechanization and even automation are evident in farming operations and related activities. Still further, an increasing demand for grain bins is evident in rural areas because increasingly larger, mechanized farming operations have opted to rely on their own storage facilities as a way to cope with fluctuations in grain prices. Consequently, there has been a long felt and now an urgent need for a grain bin lifting system that will permit operators to construct a grain bin with a minimum of labor.